1. Field of the Invention
The invention relates generally to electric power distribution systems and, more particularly, to socket assemblies for meter centers. The invention also relates to jaw assemblies for meter socket assemblies.
2. Background Information
Meter centers including a number of watt-hour meters are commonly used for metering electric power delivered to the tenant(s) of a residence (e.g., without limitation, a single family home; an apartment building) or commercial site (e.g., without limitation, an office complex).
A typical electrical meter center 1 is illustrated in FIG. 1. The meter center 1 includes a cabinet 3, having a plurality (only one is shown in FIG. 1) of meter socket assemblies 5. Each meter socket assembly 5 includes a plate member 7, to which the various components of the socket assembly 5 are secured. Electrical power is supplied to the meter center 1 by feeder buses 9. Feeder buses 9, which typically consist of three phase buses and a neutral that are electrically connected to the utility lines (not shown), extend horizontally from the cabinet 3, as shown in FIG. 1. A pair of vertical supply buses (not shown) is electrically connected to the feeder buses 9 within the cabinet 3. Each meter socket assembly 5 mounts a meter 11 for each tenant circuit and electrically connects the meter 11 to the feeder buses 9 and the supply buses (not shown). Typically, the electrical connections between the meter 11 and socket assembly 5 are made by plug-in jaws 17, which engage corresponding stabs 19 on the meter 11. The use of the plug-in jaws 17 within the meter socket 5, and corresponding stabs 19 on the back of the meter 11, permits the meter 11 to be removed from the socket 5 when servicing the meter 11 is desired.
In known designs, the connectors which incorporate the plug-in jaws were bolted to the plate member and to a corresponding one of the feeder buses or supply buses. This resulted in roughly 20 bolted connections in the electrical current path. Such connections required labor to complete and were subject to heating if they became loose.
U.S. Pat. No. 5,951,324 discloses a socket assembly, which is intended to overcome the disadvantages of the multiple bolted connections. The socket assembly provides a plate member having a plurality of through apertures and double ended fastenerless meter jaws extending through the apertures with one end of each double ended meter jaw projecting from opposing first and second sides of the plate member. Assembly of the socket assembly involves pushing one end of each jaw into a corresponding aperture until a pair of locking tabs pass through the aperture and expand outwardly to lock the jaw in place. This eliminates current-carrying joints requiring fasteners, which can become loose between the meters and the supply and tenant buses. This also requires relatively less labor to install and remove meter sockets.
Despite these improvements, there are drawbacks to the above proposal. One such drawback occurs when installing a meter having a plurality of stab contacts that must be engaged with the plural jaws on the socket assembly. Slight misalignment of the meter or variations in clamping force of the jaws can result in high insertion forces being encountered when inserting the stab contacts of the meter into the jaws of the socket assembly. Such high insertion forces can sometimes cause jaw spring clips to become misaligned or be forced through the socket base leading to improper contact engagement and damage to the meter and/or meter center and potentially complete installment failure.
Accordingly, there is room for improvement in meter centers, socket assemblies for meter centers, and in jaw assemblies therefore.